The present invention relates to a device for examination, sampling or extraction at a precise point under a slab, and can be applied in particular to dangerous products emptied for long-term storage in silos whose ceiling is formed by a protective cover-slab pierced by a single opening, generally in the centre, and normally closed.
When a sampling or examination of a sample of the contents of the silo is decided, in the present state of the art it is normal to lower an appropriate mechanism suspended from a support cable into the silo through the opening. The mechanism can be a grab in the case of solid samples or an agitating and pumping unit for liquid or loose samples. But thus it is only possible to make samplings or examinations easily in a vertical direction from the opening. In order to proceed elsewhere, the end of the cable is pushed aside guiding it by rods engaged obliquely through the opening, which is time-consuming, not very precise, can present dangers and in general does not allow access to the edges of the silo whose width is often about ten meters.